This is the first report for this project. The project consists of the creation of 2 important tools for measuring T-cell receptor diversity. The first, is the use of high-throughput sequencing to measure the diversity of T-cell receptor rearrangements. The strategies and protocol development are ongoing and being done in collaboration with Danny Douek's lab in the NIH VRC. The second tool is a functional measurement of diversity by stimulating patient T-cell samples with peptide libraries. This project is under development within our lab at this time as well. These two tools will be used to better characterize the TCR diversity of two important patient groups. The first is those with a predilection towards infections which would appear to require T-cells, but who have normal appearing lymphocyte subsets. We hope to define holes in the TCR repertoires of these patients which could explain their infections. The second is in severely atopic patients, whose repertoires may also have similar "holes" but for whom the remaining reactive T-cells therefore develop an abberantly atopic, as opposed to absent response to a given antigen. These patient cohorts are being assembled now, and as one might expect there are patients in these cohorts with both atopy and infecious predilection. We also hope to apply T-cell receptor repertoire studies to allergen-reactive T-cells, and have already begun to obtain data regarding the TCR sequences of Th1 versus Th2 allergen reactive T-cells.